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- Author or Editor: Monica Ozores-Hampton x
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Iron (Fe) deficiency is a frequent nutritional problem in Florida vegetable crops because of leaching of Fe fertilizer from the soil, poor soil aeration, low soil organic matter (SOM), temperature, high soil pH and/or water bicarbonate content, and interactions with high levels of manganese (Mn) and calcium (Ca). Most Fe-deficient plants are yellow and stunted, with symptoms on younger leaves near the top of the plant because of Fe immobility and poor translocation resulting in interveinal chlorosis. Iron deficiency in tomato (Solanum lycopersicum) is characterized by a drastic reduction of leaf chlorophyll content at first at the base of the leaves (bleached leaf) ending in necrotic spots. Iron deficiency can have a significant economic impact depending on the timing of the deficiency during the crop production cycle. Furthermore, crop genotypic variations influence the ability of root systems to acquire Fe. The objective of this article was to describe current methods used by vegetable growers to correct Fe deficiency and to evaluate their effectiveness in tomato, pepper (Capsicum annuum), bean (Phaseolus vulgaris), and eggplant (Solanum melongena) production in Florida. A survey was conducted in the major vegetable production areas in Florida during 2012. Results from the survey indicated that since Fe availability depends on complex soil and environmental factors, there was no reliable soil test method that can predict Fe deficiency on vegetable crops in Florida. Production areas surveyed with calcareous or alkaline soils that are often due to over-liming, Fe becomes unavailable because of significant reduction of Fe. Production practices for those areas were not to use calcitic lime to raise Ca levels, especially if the pH is adequate (6.5). Instead, gypsum or calcium nitrate was recommended for soil Ca. The survey indicated that Fe sulfate (inorganic form) is the most commonly used Fe fertilizer in Florida. However, chelates of Fe were effective but expensive Fe alternative. Among chelate sources, ferric ethylenediaminediaminedi-o-hydroxyphenylacetic acid was frequently the preferred chelate fertilizer for soil application, but it is an expensive option. Soil acidification to lower the soil pH was also used to improve soil Fe availability. Organic matter in animal manures and composts was used as an effective alternative to increase Fe with positive results in Florida tomato production. However, the survey indicated that Fe applied to the soil was converted into unavailable forms especially under high soil pH, thus foliar application was used if Fe deficiency symptoms were observed early in the production cycle.
Compost is primarily a soil-amending product that may improve soil quality and the productivity of organic and conventional vegetable crops. Growers can use compost as a soil conditioner or as nutrient source to supplement the fertility program in vegetable production. Nutrients such as nitrogen, phosphorous, and potassium may be low. To lower the environmental impact of high compost application rates and protect water supplies from excessive nutrient runoff or leaching, or an excessive soil nutrient buildup, compost should be applied to match the nutrient needs of a crop. Compost quality use guidelines for assessing compost quality for use in vegetable production are limited. The objective of this paper is to present guidelines for determining compost quality for use in organic or conventional vegetable production.
This review integrates information from common organic amendments used in conventional vegetable production, including 1) cover crops (legumes and nonlegumes), 2) compost generated from yard wastes, biosolids, municipal solid waste (MSW), animal manures, and other biodegradable waste by-products, and 3) raw animal manure (with and without bedding). Environmental monitoring has shown elevated nitrate concentration to be widespread in both surface and groundwater, often occurring in regions with concentrated horticultural production. Therefore, the objective of this review was to calculate the nutrient content from organic amendments, since these are not considered nutrient sources. Common organic amendments affect soil bulk density, water-holding capacity, soil structure, soil carbon content, macro- and micronutrients, pH, soluble salts, cation exchange capacity (CEC), and biological properties (microbial biomass). The first step in building a conventional tomato (Solanum lycopersicum) fertility program will be to take a soil sample and send it to a soil laboratory for a nutrient analysis. These results should be compared with the local crop recommendations. Second, select the organic amendments based on local cover crop suitability and availability of compost, raw animal manure, or both. Then, determine the nutrients available from cover crops and other applied organic amendments and use inorganic fertilizer sources to satisfy the crop nutrient requirements not supplied from these other sources.
The purpose of this article is to review nitrogen (N) controlled-release fertilizer (CRF) research methods used to measure nutrient release from CRFs. If CRF-N release patterns match vegetable crop needs, crop N uptake may become more efficient, thus resulting in similar or greater yields, reduced fertilizer N needs, and reduced environmental N losses. Three methods categories to estimate N release are: laboratory; growth chamber, greenhouse, or both; and field methods. Laboratory methods include a standard and accelerated temperature-controlled incubation methods (TCIMs); methods incubate CRF using selected time periods, temperatures, and/or sampling methods. Accelerated TCIMs, in contrast to the standard method, allow for shorter incubation periods. Growth chamber and greenhouse methods, including column and plastic bag studies, may be used to test new CRF products in conditions similar to particular vegetable production systems. However, the column method predicts N release from CRFs more effectively than the plastic bag method because of ammonia volatilization and lower N recovery rates associated with the bag method. Both field methods, pot-in-pot and pouch methods, are viable vegetable research options. The pouch method measures N remaining in the CRF prill and the pot-in-pot method measures N released from the CRF, thus each method can be applied to different research objectives. Nitrogen released during incubation may be measured using methods such as total Kjeldahl N (TKN), prill weight loss, combustion, colorimetric, or ion-specific electrodes. The prill weight loss method is the least expensive but can only be used with urea CRF. Thus, the CRF-N source(s) and research objectives will determine the appropriate N analysis method. More research needs to be completed on correlations of field and laboratory CRF extractions. Field release methods should be considered the most reliable indicator of CRF-N performance until a laboratory method reliably predicts CRF-N expected field response.
In 1988, the Florida Legislature passed the Solid Waste Management Act that affected the solid waste disposal practices of every county in the state. With legislation directly affecting the industry, organic recyclers and Florida Department of Environmental Protection (FDEP) regulators recognized a need to establish a professional organization that could serve as a unified industry voice, and foster high standards and ethics in the business of recycling and reuse of organic materials. In December 1994, a meeting was held to discuss the formulation of a Florida organic recycling association which became known as the Florida Organics Recyclers Association (FORA). FORA's first major contribution to the industry was the development of a recycling best management practice manual for yard trash in 1996. The second major project undertaken by FORA was a food waste diversion project which sought to promote an increase in food waste recovery and reuse. In Spring 1999, FORA became the organic division of Recycling Florida Today (RFT) further unifying recycling efforts within the State of Florida. In an attempt to address mounting concerns regarding industry marketing and promotional needs, RFT/FORA developed an organic recycling facility directory for the State of Florida in Spring 2000. Most recently RFT/FORA developed an organic recycling facility operator training course outline to assist the FDEP in identifying industry training needs. From its modest beginnings in 1994, to future joint programming efforts with the University of Florida's Florida Organic Recycling Center for Excellence (FORCE), RFT/FORA continues to emerge as a viable conduit of educational information for public and private agencies relative to organic recycling in Florida.
Commercial citrus (Citrus sp.) groves in Florida use an average of 150 lb/acre (168 kg·ha-1) of elemental nitrogen (N) per year. There are about 853,000 acres (345,000 ha) of commercial citrus requiring about 63,975 tons (62,652 t) of N. At an average analysis of 12% N, about 533,125 tons (483,811 t) of blended nitrogenous fertilizers are applied to citrus annually. To meet this annual N demand from compost, it would be necessary to produce 3,198,750 tons (2,901,906 t) of 2% N compost. The market for high-quality compost products in Florida is far greater than the current or projected production capacity of the state. As long as the cost benefits of compost are clear to citrus growers, demand will always exceed supply. Not all composts are equal in their nutrient availability. The best composts for use as fertilizers are derived from sewage sludge or biosolids, municipal solid waste and sludge, food waste, and/or animal manure combined with a bulking agent such as sawdust or wood chips. Composts made from wood waste as their only feedstock contain large amounts of lignin and cellulose to break down within a reasonable period to directly offset chemical fertilizers. Ultimately, they will mineralize in the soil and provide all of the benefits described earlier, but their rates of availability are in years rather than months, like the other composts.
This publication summarizes the factors influencing controlled-release fertilizer (CRF) nutrient release, CRF placement, CRF rate, and CRF application timing for the two major seepage-irrigated vegetable production systems (plasticulture and open-bed) in Florida. One of several best management practices for vegetable production, CRF helps growers achieve total maximum daily loads (TMDLs) established in Florida under the Federal Clean Water Act. Several factors intrinsic to CRF and to the vegetable production systems affect CRF nutrient release, making implementation of CRF fertility programs challenging. Increasing or decreasing soil temperature increases or decreases nutrient release from CRF. Soil moisture required for uninhibited plant growth is within the soil moisture range for optimum CRF nutrient release. CRF substrate affects nutrient release rate, which is inversely related to coating thickness and granule size. Soil microbes, soil texture, and soil pH do not influence nutrient release rate. Field placement of CRFs in seepage-irrigated, plasticulture, and open-bed production should be in the bottom mix at bed formation and soil incorporated or banded at planting, respectively. In plasticulture production systems, soil fumigation and delayed planting for continuous harvest may add a 14- to 21-day lag period between fertilization and planting, which along with different season lengths will influence CRF release length selected by growers. Using a hybrid fertilizer system in plasticulture production or incorporating CRF at planting in open-bed production allows for up to a 25% reduction in the nitrogen (N) rate needed.
With the development and implementation of best management practices (BMP), extension educators are facing a new and unexpected combination of challenges and opportunities. Because the BMP mandate requires a combination of research, demonstration, and outreach, it may affirm the relevance of the land grant mission in the 21st century, engage universities in interagency alliances, and help rediscover the wonders of the proven extension method. The extension approach to water and nutrient management needs to shift from “pollute less by applying less fertilizer” to “pollute less by better managing water.” Applied research is leading to advances in areas such as nutrient cycles and controlled-release fertilizers. At the same time, universities need to walk a fine line between education and regulation, address perennial issues of overfertilization, and consider the reformulation of recommendations that are now used in a quasi-regulatory environment. A combination of education, consensus, and novel approaches is needed to adapt the rigor of research to a multitude of growing conditions and risks of nutrient discharge in order to comply with U.S. federal laws and restore water quality.